/*
 * Copyright [2021-present] [ahoo wang <ahoowang@qq.com> (https://github.com/Ahoo-Wang)].
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *      http://www.apache.org/licenses/LICENSE-2.0
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package me.ahoo.wow.models.tree

object Trees {
    fun <F : Flat, L : Leaf<L>> Iterable<F>.toTree(root: L, toLeaf: (F) -> L): L {
        val categories = map {
            toLeaf(it)
        }
        return buildTree(root, categories)
    }

    private fun <L : Leaf<L>> buildTree(parent: L, categories: List<L>): L {
        val children = categories.filter {
            parent.isDirectChild(it)
        }

        if (children.isEmpty()) {
            return parent
        }
        val treeChildren = children.map {
            buildTree(it, categories)
        }
        return parent.withChildren(children = treeChildren)
    }
}
